The Space Shuttle, or officially the “Space Transportation System” (STS) is quite an aged technology, needing special Space Shuttle Fuel.
Some Space Shuttle Facts: The system was originally designed in the 1970s, while Nixon gave the presidential order to build a reusable, landing spacecraft in 1969.
The Space Transportation System (STS) uses different fuels and rockets/engines to go into space.
On the one hand there are the famous two Solid Rocket Boosters on the side of the main tank, one of which was causing the Hydrogen explosion in 1986 ripping the Challenger (STS-107) to pieces.
I still remember how devastated I felt. The Space Shuttle Program was one of the hopes of my youth. I still remember how I read every article I could find about this catastrophe.
And it shows just how dangerous Hydrogen as a fuel can be. It is highly explosive.
But back to the Solid Rocket Boosters. They burn with solid fuel and provide 83% of the force needed to lift the Shuttle into orbit. They have 80 % more power than the famous F-1 engine lifting the Saturn to the moon.
The propellant or fuel for the Solid Rocket Boosters is called Ammonium Perchlorate Composite Propellant (APCP), with Ammonium Perchlorate being the biggest ingredient. But the actual fuel is Aluminium, while Ammonium Perchlorate is the oxidizer. The chemical reaction (oxidization) – see chemical energy – delivers the power to liftoff.
What I found interesting is that Aluminium, once ignited, is actually a fuel. I didn’t know that. But Aluminium has a energy potential of 31 MegaJoule/kg. Enough to lift a Space Shuttle into orbit.
But the Space Shuttle’s Solid Rocket Boosters only do the heavy lifting in the beginning, for about 240 seconds.
Space Shuttle Fuel: Hydrogen
On the other hand the Shuttle has its own main engine cluster composed of 3 engines.
Space Shuttle Discovery’s external fuel tank from STS-124, after separation. The blue background is Earth as viewed from the Shuttle. Courtesy NASA
These engines get their fuel during start from the external tank. This tank contains liquid Hydrogen and Liquid Oxygen…when brought together, they show a formidable, energetic reaction…
To keep Hydrogen – which is highly reactive and dangerous – liquid, it needs to be pressurized and cooled down close to the absolute zero point.
So the Space Shuttle uses Hydrogen as fuel and is a a Hydrogen powered Vehicle with a Hydrogen engine.
And whereas the other fuels used for the Space Shuttle (Boosters, Orbital Maneuvering System) are highly toxic, Hydrogen is reusable, burns to water (3 H2+ 3 O2= 3 H2O+O3).
So the Space Shuttle Orbiter’s main engines are zero emissions Hydrogen engines.